Metal Spinning (or spin forming) is a process where a tube or a disc of metal is rotated at high speed and transformed into an axially symmetrical object. Metal spinning is usually performed on a vertical or horizontal lathe using CNC controls or hand processing. So, by its very nature, metal spinning is an example of a technology that has spanned a timeframe stretching from the days of hand-tooled craftwork to the modern computer era. How do the two techniques compare, and how do they complement one another? Good questions. Let’s take a look.
During hand spinning, the operator controls both the spinning speed and forming forces. Hand spinning is a craft where the operator subtly works with the material to create a form. This is done through precise motions rather than brute force. A form is created by an operator who can feel the structure of the metal, its grain, its hardness, and its willingness to move in one direction or another. With one hand, the operator uses the spoon to shape the work piece over the block, while the other hand applies the necessary lubricants or additional pressure to assist the process. There are an infinite number of tool designs that can be forged in steel to assist in spinning a variety of shapes.
The products created by hand spinning cover a wide range: prototypes of beverage cans, mechanical parts for satellites and aircraft, components for semiconductor manufacturing equipment, large parabolic antennas, and so on—many products of all different sizes. The use of hand spinning has many manufacturing and economic benefits.
There are several advantages of automatic spinning, as well. For example, it removes the many uncertainties of operator skill and operator-to-operator variations, making spinning highly repeatable and accurate. After a CNC machine has been programmed (or ‘trained’), it can automatically execute the instructions, hydraulically applying predetermined forces for predetermined lengths of time on precise areas of the blank, creating fairly identical parts. Such machines can automatically shape the part, trim or otherwise finish the edges, and eject the finished part. These programs can also be transferred from machine tool to machine tool, stored for future processing, and easily updated and refined for future runs. The use of highly skilled metal spinners is no longer necessary to run these machine tools. However, an operator must still be knowledgeable about the intricacies of metal spinning, as well as the control software required to run the part.
An ideal machine shop has both – hand spinning as well as CNC spinning capabilities. Manufacturers choosing to work in metal spinning can tap into the high production capabilities of an automated shop floor, but they may also require manual spinning to create more intricate architectural and decorative products. Combining both of these techniques allows for the mass production of the bulk of a product line through CNC automation, while finishing it up with hand spinning, to create a product that is hand-crafted. Additionally, shorter run productions may be more cost-effective when completed with hand spinning, removing the time it takes to set up and program a CNC machine.
For more, check out our new, free, e-book "Hand Spinning and CNC Spinning."